JOHNSTON, R.I. — Rhode Island’s first commercial-scale anaerobic digester still isn’t ready, but company officials say it's getting closer to completion. And when it’s operational, New England's largest digester may be a test case for similar facilities in neighboring states with food-diversion laws.

Rhode Island’s compost law, passed in 2014, requires large institutions such as supermarkets and food makers to divert their organic scrap to a farm, food pantry, compost facility or anaerobic digester, as long as such a facility exists within 15 miles. So far, only a smaller-scale compost facility is operating in Charlestown — Earth Care Farm has been composting food scrap for 40 years. The Compost Plant has proposed a facility in Warren.

In recent years, smaller digesters have been built in Massachusetts that service a single facility, like a Stop & Shop distribution warehouse in Freetown, Mass. In Dartmouth, Mass., a 12-ton-per-day food scrap to biogas anaerobic digestion facility opened in 2014 at the Crapo Hill Landfill. A single digester, or digesters, intended to serve an entire state or region has yet to materialize.